Archived ///// Charging gremlins gonna leave me stranded ? /////

[AndrewKing]

HI Guys,

I have a 1997 Dodge 3500 that had started cranking a little slowly the other day. I looked at my volt meter and I noticed the needle was somewhat lower than usual so I put a digital voltmeter to the driver side battery....With the engine running at idle, the voltmeter read 13.2 volts.

The batteries are about 2 years old and the alternator is fairly new also (the old one developed squeaky bearings after about 180K miles so I replaced it with a
new unit from NAPA about 1 year ago). The serpentine belt and tensioner are good.

Today, I replaced the alternator with a new one (from NAPA) ....After putting everything back together and cleaning up all the battery terminals / connections I put the digital meter on the driver side battery hoping to see something in the 14. Volts range but to my disappointment I only saw about 13.4 volts at idle (didn't really seem to want to go up with increased engine RPM either).

I tried tracing the wires from the alternator to look for an external voltage regulator but I didn't see it and that is why I though it may be internal to the alternator (hence my replacing the alternator earlier today)

I fully charged the batteries today BUT tomorrow is the start of a new work week and my truck is my daily driver and I really don't want to run out of juice out in the middle of nowhere ......

So what do you think?...Is it OK to run charging at only 13.4 volts? Will this damage my batteries and leave me stranded somewhere....I think it used to charge
around 14.5 Volts but something is now amiss....What should I be looking for to correct this....I did not see any external voltage regulator like on my first gen dodges....

Thanks in advance for any and all help.

Andrew

 

[GAmes]

The voltage regulator is part of the PCM. There is a battery temp sensor under the drivers side battery. It works in conjunction with the voltage regulator and if the battery is hot the charging voltage should go down. The testing procedure for the temp sensor is in the factory service manual, along with the theory of operation of the charging system. Autozone carries the temp sensor if it tests faulty.

 

[AndrewKing]

HI,

Thanks for the reply....I will check under the battery tomorrow AM before heading out to see if there is a temp sensor (I suppose it wouldn't hurt changing it out just in case?)....I don't recall seeing one but then again I wasn't really looking that hard for anything under battery and it's been a couple years since I replaced the batteries.

Just curious but where is the PCM located?....I am guessing if the battery temp sensor doesn't fix the issue I have to pop for a new PCM?

Thanks again...

Andrew

 

[GAmes]

I will check under the battery tomorrow AM before heading out to see if there is a temp sensor (I suppose it wouldn't hurt changing it out just in case?)...

Seriously?? You are going to check to see IF there is a battery temp sensor? You think I made it up??

I'm guessing you don't have a FSM? You would rather throw parts at a perceived problem than buy a manual, the most used tool in the shop?

But, just this once, I took the time to check my '97. A couple hours ago I shut if off after a two hour drive. Prior to starting the engine the battery was at 12.20 volts. At an idle it is 13.22 OMG!!!!! Do I need to run out and buy a new PCM??? Uh, no, the voltage regulator is reading the temp of the battery (it is about 90f here right now) and charging it accordingly.

 

[AndrewKing]

HI,

No, I wasn't doubting that there SHOULD be a battery temp sensor somewhere, its just that I never looked for it and can't ever recall seeing it...it could have been that the previous owner of the truck did away with it for unknown reasons (like the stering stabilizer shock that was missing from the front end of my truck when I bought it from him which was probably part of my death wobble issue) but most likely (hopefully) the battery temp sensor is there....

I appreciate you posting your voltage numbers; its just on my truck the factory gauge ALWAYS read above the 14 V level and then coincidentally, when I noticed the truck wasn't cranking with as much vigor as before that I noticed the factory voltmeter started reading somewhat BELOW the 14V level on the factory gauge...that's what prompted me to hook a digital volt meter to the battery to see what was going on (also in some of my reading, it seemed like lots of people think that the charge level should be in the 14+ volt range with 14.5 V seemingly being "ideal")?

About the only other thing I can think of that was a little unusual was that the other day (July 3) my other truck broke down and , while I was waiting for the tow truck to get my 1989 dodge, I was in this dually idling for about 35 minutes....ironic that this should happen after that prolonged idle...who knows, but I will keep an eye out on the charge rates....I'm still just a little paranoid tho....but I still have to head out to work tomorrow (I'll probably bring an extra battery and a jump box along "just in case").

Thanks for your help and I'll probably have to look into a FSM as well....

Andrew

 

[GAmes]

Good grief, I wonder why I'm responding at all. First, there is no chance the previous owner "did away with it". The alternator will not charge at all if the sensor is faulty, which means to me that it won't charge if the sensor is disconnected.

I guess you skipped over " It works in conjunction with the voltage regulator and if the battery is hot the charging voltage should go down" so pay attention, I'll type slowly. This is a quote from the FSM.

The battery temperature sensor is used to determine the battery temperature and control battery charging rate. This temperature data, along with data from the monitored line voltage, is used by the PCM to vary the battery charging rate. System voltage will be higher at colder temperatures and is gradually reduced at warmer temperatures.

 

[Missouri Mule]

You can not see the battery temp sensor it is under the battery tray! Your voltage seems to be OK. The hotter the outside temp and engine compartment less voltage. Colder it is outside the EVR (electronic voltage regulator) will crank the volts into the 14 range. The EVR uses the temp of the battery and line voltage for output of alternator.

The starter could be going especially if it a napa one. When starting the engine try pressing down on the go pedal. If it starts easier its the starter.

My napa starter (mechanic put the piece of junk on) needed to have the go pedal down a little it finally gave up the ghost a few months later. Lucky my Mule was parked in the drive way.( napa lasted three years my original lasted 15 years).

 

[CrewCabDiesel]

Andrew, not sure about a 97 charging system but a lot of electrical problems lead back to bad connections especially the ground circuit. I do know on my 2004 if one battery has a bad connection it causes an over charge on the other battery, might work in reverse on your truck.
As for GAmes, chill out! not everyone is an expert like you!

Hope things work out Andrew
Kyle

 

[GAmes]

As for GAmes, chill out! not everyone is an expert like you!

Yup, that's me. Expert manual reader and one who pays attention when I'm told something.

 

[bigblock_doc]

Come on now, play nice. Not all of us are pros like me. ha ha
Make sure to charge and load test each battery. One bad one could
cause the same type of reading.